Quasarscelestial objects so far away that their light takes

Question

Quasarsâ€”celestial objects so far away that their light takes at least 500 million years to reach Earthâ€”have been seen since 1963. For anything that far away to appear from Earth the way quasars do, it would have to burn steadily at a rate that produces more light than 90 billion suns would produce. But nothing that burns at a rate that produces that much light could exist for more than about 100 million years.

If the statements above are true, which one of the following must also be true on the basis of them?
(A) Instruments in use before 1963 were not sensitive enough to permit quasars to be seen.
(B) Light from quasars first began reaching Earth in 1963.
(C) Anything that from Earth appears as bright as a quasar does must produce more light than would be produced by 90 billion suns.
(D) Nothing that is as far from Earth as quasars are can continue to exist for more than about 100 million years.
(E) No quasar that has ever been seen from Earth exists any longer.

Paul · Answer

45 sec. Are you sure C is the answer? I would go with E
What if a star 200 million years away appears to be as bright as a quasar? And what if that star produces only the light of 30 billion suns? E is safest answer because if quasars take 500 million years to reach Earth and live less than 100 million years, by the time they reach Earth, they are extinct.

SimbaLion · Answer

I agree with Paul. E should be the answer. Easy example would be...what if something as bright as a quasar (as seen from earth) were directly next to earth? surely it wouldn't have to be the brightness of 90 million suns?

SigEpUCI · Answer

Quasers > 500 million light years from earth
Light to reach that far requires burn limit of 100 million years.

Therefore, seen from earth (500 million travel time) - 100 milllion life, equals quasar ended existance AT LEAST 400 million years ago.

The answer is definately E.

mba · Answer

Somehow I am not very sure about (E),

Paul: Can you help refuting choice (D).

carsen · Answer

Hi (i am back after the vacation) and this is first post.... :-D

Quasarsâ€”celestial objects so far away that their light takes at least 500 million years to reach Earthâ€”have been seen since 1963. For anything that far away to appear from Earth the way quasars do, it would have to burn steadily at a rate that produces more light than 90 billion suns would produce. But nothing that burns at a rate that produces that much light could exist for more than about 100 million years.

If the statements above are true, which one of the following must also be true on the basis of them?
(A) Instruments in use before 1963 were not sensitive enough to permit quasars to be seen.
(B) Light from quasars first began reaching Earth in 1963.
(C) Anything that from Earth appears as bright as a quasar does must produce more light than would be produced by 90 billion suns.
(D) Nothing that is as far from Earth as quasars are can continue to exist for more than about 100 million years.
(E) No quasar that has ever been seen from Earth exists any longer.

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SigEpUCI · Answer

This question is from the LSAT, i remember seeing it when i was studying testmasters LSAT prep material before i took that exam last year. 

Testmasters had an entire problem classification for this problem type, they called it "Must Be True" type, and essentially, you look for a statement that must be true, given whats in the stimulus. As per D,
we don't know anything about the brightness of the objects relative to their distances, hence we can't support that preposiiton.

Bhai · Answer

Quasars are an example in the question. There is generic information given about anything and nothing. So why not D. I see E has its own merits but D can also qualify to be an answer. Please explain.

SigEpUCI · Answer

D says "Nothing that is as far from Earth as quasars are can continue to exist for more than about 100 million years."

D is incorrect becuase it may or may not be true. A correct answer for this question type MUST be true given the support from the stimulus. 

if D said "Nothing that is as far from Earth as quasars AND CAN BE SEEN FROM EARTH can continue to exist for more than about 100 million years"
then it would be a correct answer. Notice D does not say that the object needs to be visible from earth, only that it is far from earth.

dj · Answer

good discussion guys. E is the answer.

1) nothing could burn for more than 100 million years
2) quasars' light reaches in 500 million yrs.

quasars will die before their light reach earth.

Quasarscelestial objects so far away that their light takes

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